The purpose of this project is the examination of the amino acid and glucose metabolism of Peptostreptococcus anaerobius. This organism has been shown to have a unique nutritional relationship with the host salivary secretions: oral isolates have an absolute dependancy on the presence of proline in the medium for optimal growth; in its natural habitat the proline requirement is met by the proteins of the salivary secretions which contain as much as 30% of this cyclic amino acid. P. anaerobius ATCC 27337 has been shown to couple the reduction of proline to the oxidation of glucose and amino acids in Stickland-like reactions. The reductase activity towards proline was maximal in exponentially growing cells. Leucine reductase activity however was only found in stationary phase cells. No alterations to levels of these activities were detected in cells grown at different growth rates in a continuous culture apparatus. When grown in the absence of glucose alanine is the principle amino acid oxidised by this organism with the formation of acetic acid, ethanol and CO2. Both non-glucose grown and glucose grown cells were able to metabolize this amino acid in washed cell suspensions. However alanine was shown to be formed as an end-product of the metabolism of glucose in the presence of ammonia by glucose grown cells. The catabolism and synthesis of alanine by P. anarobius is currently under further investigation.